If you are pricing up an extension in Ayrshire, you will find plenty of national cost guides but very little that reflects what builders here actually charge. As a joinery and building firm based in Kilwinning, we see the real numbers on jobs across North Ayrshire every week. Here is an honest breakdown of what to expect and what changes the price.
Most single storey extensions in Ayrshire currently come in somewhere between £1,700 and £2,400 per square metre for the building work itself, finished to a plastered, decorated standard. That means a modest 20 square metre extension, roughly 4m by 5m, typically lands between £34,000 and £48,000 before you add a kitchen or high end finishes. Ayrshire prices generally sit below the central belt cities, and well below the figures you see in UK wide guides written with the south of England in mind.
Two storey extensions are better value per square metre because the foundations and roof are shared across two floors. Expect roughly £1,500 to £2,100 per square metre, so a two storey addition of 40 square metres in total might range from £60,000 to £84,000. These are guide figures, not quotes. Every plot, every house and every specification is different, which is why any builder giving you a firm price before visiting the site should be treated with caution.
The biggest cost drivers are usually below the ground and above your head. Poor ground conditions, old drains that need moved, or a sloping site can add thousands before a single wall goes up. Parts of Ayrshire have made ground or clay that needs deeper foundations, and you often will not know until the trial holes are dug. At roof level, a flat roof is cheaper than a pitched one, but a pitched roof in matching slate or tile usually looks right on older Ayrshire stone and rendered homes and tends to satisfy planners more easily.
The specification you choose matters just as much. Bifold or sliding doors, underfloor heating, a vaulted ceiling with roof lights, or knocking through to create a full open plan kitchen all add real money. Knocking through also means steelwork, and a structural engineer's design plus supply and installation of beams typically adds £2,000 to £5,000 depending on the spans involved.
The build cost is not the whole story. In Scotland you will need a building warrant from North Ayrshire Council, or the relevant Ayrshire authority, and possibly planning permission if the extension falls outside permitted development. Architectural drawings, structural engineering, warrant fees and any planning application usually add £3,000 to £7,000 in total for a typical domestic extension. It is money well spent, because a good set of drawings gets you comparable quotes and far fewer disputes on site.
Remember that VAT at 20 per cent applies to extension work from a VAT registered builder, and check whether quotes you receive include it. It is also sensible to hold a contingency of around 10 per cent of the build cost for the unknowns, particularly on older properties where opening up walls can reveal surprises.
The most useful thing you can do is get drawings done first, then ask two or three local builders to price the same specification. A quote should itemise what is included: groundworks, structure, roofing, windows and doors, first and second fix joinery, electrics, plumbing, plastering and decoration, plus what is excluded, commonly the kitchen units, floor coverings and landscaping. If one price is dramatically lower than the others, something has usually been missed or assumed, so ask questions before you sign anything.
Ask each builder about payment stages too. Staged payments tied to completed work are normal and fair. Large deposits up front for labour are not, though a deposit to secure materials like windows or steel is reasonable. A local firm should be happy to show you extensions they have completed nearby and let you speak to the owners.
Generally yes. Labour rates in Ayrshire are lower than in Glasgow, Edinburgh and most of England, so budget guides written for the wider UK often overstate what you will pay here. Materials cost much the same everywhere, so the saving comes mainly from labour.
Once the building warrant is granted, most single storey extensions take 10 to 14 weeks on site, weather permitting. Add two to four months beforehand for drawings, engineering and the warrant approval process, which varies with council workload.
Not always. Many single storey rear extensions fall under permitted development in Scotland, but you will still need a building warrant in every case. Listed buildings, conservation areas and larger or two storey extensions usually need planning permission, so check with the council or your designer before committing money.
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